Hartke 15" element?

Hi. I got (for free) a Hartke 15" aluminium speaker element, 200w 8 ohm (with the 3" coil), and I intend to build a additional cab for my rig.
Does anybody have the specs for the element,or at least know who's the actual manufacturer of the element.
I would at least need to know the resonant frequency but preferably all the other specs also.
If I can't get the driver specs, I would be greatful for the cabin dimensions (or volume) and the diameter and lenght of the reflex tubes fitted on a Hartke 15 ", 200w cabinet.